A conceptual illustration showing a "Please take a number" dispenser in space
Nicolas Ortega

Space

Who gets to send radio waves in space?

Satellites aren’t much use if they can’t communicate

Jun 26, 2019
A conceptual illustration showing a "Please take a number" dispenser in space

It’s getting crowded up there. Flocks of cubesats, fleets of orbiting cameras, and the first broadband internet mega-­constellations from the likes of SpaceX, Amazon, and OneWeb are quickly filling low Earth orbit. If all the services launch as planned, there could soon be 10 times as many satellites operating in orbit as there are today.

The rise in dangerous space junk is a concern. But there’s a more immediate headache for satellite operators: a tightening squeeze on the radio frequency spectrum required to operate from orbit. Could space startups squabbling over getting their fair share actually hold back this nascent industry?

Electromagnetic radiation spans a wide range of frequencies and energies, but only specific bands are useful for communication to and from space. High-frequency x-rays would be dangerous; microwave signals are absorbed by the atmosphere; low-­frequency radio waves are less effective at transmitting information and require large, ungainly antennas.

Like people shouting at a party, competing signals at the same radio frequency can interfere and make communication difficult, so the spectrum needs to be parceled out in bite-size chunks for different uses. Multiplexing systems allow operators to share spectrum by finely slicing time slots and frequency channels as well as by encoding signals so that many different messages can be transmitted simultaneously. But bands of frequency still need to be assigned to particular users, to avoid interference that would make radio spectrum unusable. Many of the most desirable frequencies for orbital links were allocated to traditional radio and TV broadcasts long before the first satellites were launched. Now, as the heavens fill with more satellites, the scramble for radio frequency slots is growing ever more fractious. Regulators are being asked to deal with more companies, more spacecraft, and more disputes than ever before. Paperwork can stretch out for years, even as enthusiastic startups attempt to disrupt a conservative industry.

Swarm Technologies is no stranger to regulatory tussles. When this small Silicon Valley startup launched four tiny experimental satellites in 2018, it neglected to obtain the necessary authorization from the US Federal Communications Commission, one of the agencies whose approval needs to be granted before launch can take place. The FCC found out and slapped the company with a $900,000 penalty.

The company now wants to launch a 150-strong constellation to communicate with the growing number of internet-­connected devices on Earth. Because its satellites are so small, and thus cheap to launch, Swarm reckons its messaging services will cost an order of magnitude less than existing satellite systems. All it needs is a few slivers of VHF radio spectrum. 

However, longtime satellite operator Orbcomm has laid claim to those frequencies for decades, and it operates one of the very messaging systems that Swarm aims to disrupt. In a petition to the FCC to dismiss Swarm’s constellation application, Orbcomm wrote that the startup “attempts to simply ignore Orbcomm’s clearly vested … spectrum rights.”

“There really are scarcity concerns in orbit,” says Thomas Hazlett, an economics professor at Clemson University and author of The Political Spectrum. “If you want to put up a satellite for communications, you may have potential conflicts with other users. There is a real need for rules to help coordinate this use.”

The International Telecommunications Union (ITU) is the body tasked with unpicking these competing claims. Formed in the mid-19th century to standardize telegraph technologies, it has helped regulate who gets to place satellites in orbit since the dawn of the space age. The agency, which also makes it possible to make telephone calls from one country to another, among myriad other regulatory responsibilities, is now part of the United Nations. But individual countries also want some say about spacecraft flying overhead. That means operators like Swarm also have to work with national agencies in the countries in which they intend to operate (in particular, the FCC controls access to the all-important American market).

Unsurprisingly, newcomers see these regulations as barriers intended to keep them on the ground. In a lengthy response to the FCC, Swarm claimed that Orbcomm has no rights to the spectrum it wants to use and that the company’s “frivolous” petition “represents nothing more than the attempt of a longtime monopolist to use the licensing process to maintain its privileges.”

Stable circular orbits around Earth are associated with particular velocities, which vary with altitude. (Satellites in elliptical orbits speed up when closer to Earth and slow down as they reach the farthest point in their orbit.) At 35,786 kilometers (22,236 miles), the orbital speed matches Earth’s rotation. Spacecraft flying directly above the equator at that altitude will appear frozen in the sky to an observer on the surface. Such geostationary slots enable a single large satellite to serve a wide geographic area, whether in relaying communications or, say, monitoring the weather.

Allowing for some elbow room between neighboring satellites, there are perhaps 1,800 useful geostationary spots on this great circle, around 400 of which have become occupied over the years. As might be expected, there is more interest in spots above rich regions like North America and Europe than above sparsely populated Pacific islands. Countries were allocated slots above their longitude, and then individual satellites were allowed to take up residence on a first-come, first-served basis.

Nicolas Ortega

At first, spectrum seemed to be a solvable problem. Not only did frequencies have to be sliced up between just a small number of operators in one area, but the same frequencies could be reused over and over again around the globe. Everyone understood the rules, says Tim Farrar of satellite consulting firm TMF Associates. 

The rules of the game are changing, however. Operators want to pack small, cheap satellites onto ride-sharing rockets and send them into low Earth orbit, or LEO. From just a few hundred or thousand kilometers up, satellites with cameras have a much better view of the planet; for communications systems, the shorter distance to the surface can save power and reduce latency. With a multitude of altitudes and orbits to choose from, there should be room for all.

Spectrum is now becoming the limiting factor in who gets to deploy new communications constellations. Satellites in LEO whiz around the planet in a matter of hours, potentially causing interference not only to one another but to every geostationary satellite they pass beneath. At first, the ITU’s solution was to do the same thing it had done for geostationary orbit: the first operator to apply to use a slice of spectrum was given priority. Everyone following would have to agree not to interfere.

But interference is a slippery concept. “Geostationary coordination is relatively straightforward,” says Diederik Kelder, chief strategy officer at LeoSat, which is planning a constellation of at least 84 internet satellites in LEO. “Whereas in [LEO] it’s a very complex thing. You need very sophisticated modeling tools to grasp the impact.”

Foreseeing a coming spectrum crunch, the FCC decided to push forward with spectrum-sharing policies where everyone planning to use similar frequencies would be considered at the same time—so-called “processing rounds” that would theoretically create a fairer playing field.

But there have been unintended consequences. More disputes have erupted as new entrants try to find regulatory loopholes or technical fixes while established operators attempt to protect their frequencies from interference, whether real or imagined. The incentive for companies to apply for frequencies as soon as possible also means that they have to file requests at the ITU and FCC long before their satellites have been built or, sometimes, even fully designed.

SpaceX is the most ambitious of the new LEO generation. In 2015, Elon Musk unveiled a plan to use a mega-­constellation of satellites called Starlink to deliver global broadband internet that would reach many developing and underserved regions. SpaceX originally asked permission to launch 4,425 satellites, but it upped that to nearly 12,000 in 2017—a constellation that the FCC finally licensed in late 2018.

In the run-up to the launch of its first commercial satellites, SpaceX tinkered with its plan yet again, asking to move some of its satellites closer to Earth and change the frequencies they would use. Its own analyses supposedly showed no new interference, but other satellite companies were not happy. Kepler, another satellite communications startup, called its claims “fundamentally misleading.” OneWeb, which plans its own mega-­constellation of more than 2,500 internet satellites, similarly said SpaceX’s interference calculations “[included] misleading operational assumptions, an incomplete analysis parameter set, and highly misleading conclusions.”

The FCC approved SpaceX’s plan, and the company launched its first 60 Starlink satellites in May. Its rivals will now have to launch their satellites hoping that their interference concerns were unfounded.

At least this spat was quickly settled. The nightmare for newcomers is that disputes can lead to interminable regulatory delays.

In 2001, for example, a company called Mobile Satellite Ventures applied to the FCC to repurpose some of its satellite frequencies for a hybrid satellite/terrestrial communications service. Ten years later the company, now called LightSquared, received a conditional waiver to proceed that was swiftly suspended over concerns that it might interfere with GPS navigation signals. LightSquared almost immediately filed for bankruptcy, but with the passing of nearly another decade, and yet another name change, Ligado Networks continues LightSquared’s fight. It has promised to reduce the power of its transmissions by over 99% yet still faces sustained pushback from nervous, and possibly jealous, aerospace competitors.

“Ligado’s decision to waste 40 MHz of satellite spectrum should not be rewarded with a windfall,” rival satellite operator Iridium wrote to the FCC in July 2018. In April, Ligado noted in a meeting with the FCC that the agency had been considering its latest application for over 1,000 days. As this issue went to press, the FCC had yet to rule on it.

Nevertheless, Ligado’s approach shows how technology could help quell squabbles. The firm was able to dramatically reduce its power requirements thanks to increasingly sensitive receivers. Multiplexing systems also continue to improve, because of both improved computing power and increasingly intricate, clever techniques for encoding and decoding signals.

High-gain antennas allow satellites to create focused spot beams targeting specific areas below them. The tighter that focus, the more often those frequencies can be reused. Other new systems plan to use even more tightly focused lasers for one satellite to communicate with another, reducing the demand for radio frequencies. New phased array technologies mean satellite signals can now be received by small and cheap electronically steered flat-panel antennas rather than the unwieldy parabolic dishes of old. GPS-equipped satellites and user terminals alike can be programmed to avoid transmitting toward rival LEO or geostationary satellites.

Some experts believe that the best way to unleash technological innovation is for regulation to take a back seat to market-based solutions, like the existing auctions for terrestrial wireless spectrum. But there is no clear mechanism for such a global spectrum auction.

In any case, though converting free allocations of satellite frequencies into tradeable rights might offer incentives for cooperation over obstruction, it would be a fraught process at a global scale. The orbital economy is already dominated by a handful of the world’s most powerful nations. Giving preferential access to those companies with the deepest pockets seems likely to perpetuate historical inequities, and to exclude developing countries with the most to gain from reaching the next technological frontier.

Not everyone sees the need for a revolution in orbit. Farrar believes that satellites and ground stations will be regularly forced to pause operation until the risk of interference subsides, thus dramatically reducing their capacity and threatening already shaky business plans. “It would be a disaster from an economic point of view if everyone gets to operate,” he says. “But it’s inconceivable that [all these companies] will do what they’ve announced they plan to do.”

In which case a tortuous bureaucracy that defers, delays, and disrupts business plans might be just what space needs.

 

Mark Harris is a writer in Seattle and a frequent contributor.